This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Preliminary analyses of FAM 3 data showed an association between skeletal size and age at menarche: We considered the 88 pure Asian, pure White or mixed Asian-White girls who had not reached menarche at Exam 1 and were seen at FAM2 and 3. Seventy four of the 88 girls had reached menarche by the end of follow-up. We found bi-iliac (maximum pelvic) breadth was strongly associated with shorter time to menarche. Further adjustment for DXA trunk and peripheral skinfolds strengthened this association. A strong correlation (Spearman r=0.73) existed for bi-iliac breadth at the 1st and 3rd exam, suggesting that this measure may track over time. In a cross-sectional analysis of the cohort examined at the 1st exam (n=198), bi-iliac breadth was independently associated positively with trunk-to-periphery fat ratio measured by skinfolds (p0.003), height (0.001), Tanner pubic hair development (p0.001) and calories from protein (p0.001), and negatively with calcium intake (p=0.01). These relationships were weaker in a similar analysis at the second exam (n=106), except for the strong association of bi-iliac breadth with trunk-to-periphery fat ratio measured by DXA or skinfolds (both p0.001). These data suggest that bi-iliac breadth might be an early and persistent marker of early maturation. The measure of bi-iliac breadth includes subcutaneous fat in its measurement. Since we have DXA skeletal images, we would like to measure biliac breadth electronically "directly" from the scan images. Bi-trochanter is another measurement of hip dimension that was not collected for this study. We would also like to take this measure electronically. There will be no new data collection from the subjects and will only consist of re-analysis of existing raw data available from the DXA exams. Further development of DXA pelvic dimensions will be valuable to understand skeletal size and determinants of early puberty.